The present invention relates to an industrial robot and in particular to an improvement in the construction of an industrial robot of the type wherein a rotary motion unit of a robot motion assembly supporting a robot arm and a robot hand is arranged on a vertical motion unit of the robot movable assembly.
A conventional industrial robot of the above-described type is provided with, as illustrated in FIG. 1, a vertical feed mechanism mounted on a robot base 10 and adapted to drive a robot motion assembly having a robot hand 30 vertically along a vertical guide 12 extending upward from the robot base 10. The robot motion assembly comprises a rotation drive means 16 including therein a rotation drive mechanism, a rotation drive motor 18, a bearing box 20, a robot housing 22 mounted on the bearing box 20, a drive motor 24 attached to the robot housing 22 for driving the extending and retracting of a horizontal robot arm 26 extending transversely from the robot housing 22, a robot wrist 28 attached to an outer end of the horizontal robot arm 26, a robot hand 30 attached to a free end of the robot wrist 28, and a wrist-rotating drive motor 32. Thus, the conventional industrial robot has an arrangement in which a rotary motion unit having a vertically extending rotating axis is disposed on a vertical motion unit having a vertical motion axis and a robot arm extending and retracting mechanism for extending and retracting the robot arm 26 is disposed in the rotary motion unit. Reference numeral 14 designates the rod of a load-compensating cylinder provided within the robot base 10 for reducing the load applied to the vertical feed mechanism by counterbalancing a downward load produced by the weights of the rotation drive mechanism, the robot arm extending and retracting mechanism, and the workpiece gripped by the robot hand 30. In the industrial robot having the above-mentioned arrangement, it is conventional to arrange electric wiring related to the rotation drive means 16, electric wiring extending to the robot arm extending and retracting mechanism via the rotation drive means 16, and piping for supplying a working fluid, such as pressurized air, to the robot hand 30 around the exterior of the industrial robot. Accordingly, it is necessary to provide electric wiring and piping of sufficient lengths and to arrange these electric wiring and piping with the help of particular retaining and holding members, such as stainless steel strips and clamping elements, in order to permit the unobstructed rotating motion of the rotary motion unit when the rotation drive means is operated. Furthermore, as the electric wiring and piping are exposed to the exterior of the industrial robot, these wiring and piping spoil the external appearance of the robot and, in addition, are liable to be damaged to such an extent that the reliability of the industrial robot is lowered.